Was it a plane? What was it?

THEORIES of what was behind the bright light that crossed the sky over Gympie and created a "boom" further north on Tuesday were many and varied.

Bundaberg Astronomy Society member Mark Sugars said descriptions of the sighting, which were reported from Gympie to Rockhampton, suggested it was a meteorite. But Gladstone's Rory Henricks said he thought he saw a plane, saying it was "shooting fireworks out of its rear".

He said at 9.20pm he was riding from town to Calliope and saw the object for a second. "Nothing, then several circular firework explosions in a line behind it, then nothing again," he said.

"I flipped my visor up to have a look around, I saw some pilot lights but lost track of it. Was moving really fast and appeared to have jet engines under each wing. I'm pretty cynical but if it wasn't a UFO it seems like someone was trying to appear like one."

Royal Australian Air Force watch keeper Corporal King said a bulk carrier KC-30A did take off from the Amberley Air Base last night so it could have been that.

Some said the object made a "boom" sound around 9.20pm.

Corporal King, who couldn't reveal his first name because of strict defence force privacy protocol, said the KC-30A had taken off from the Amberley Air Base.

"It was the only aircraft that was flying from the Amberley area during that time," he said. Why the aircraft was in the area and what path it had taken remains a mystery, as corporal King said, "I'm not at liberty to disclose that information".

UFO expert Sheryl Gottsthall said the theory it was a meteor just "doesn't gel" because "meteors don't rumble for five minutes", as one reader reported hearing.